The discovery of a bone representing humanity’s oldest known relative is something that should have scientists patting themselves on the back, but it's also got them scratching their heads.
Researchers discovered the ancient humanoid remains in a cave — known as the "Sima de Los Huesos" or "Pit of Bones" — in Spain. (Via Madrid Scientific Films)
And after extracting DNA from the femur, researchers found the specimen to be 400,000 years old. That's about 100,000 years older than the previous oldest human DNA, and 200,000 years older than modern humans. (Via ABC)
"This discovery is mind-blowing. We're talking about DNA coming from these fossils. It's much more difficult to get that out of bone fossils than out of something that's been frozen over time." (Via WDIV)
So far, so good, right? Well, there’s a twist in the story.
Scientists expected to find that the specimen was closely related to Neanderthals. (Via PBS)
But instead, were surprised to find it was related to a little-known group of ancient human relatives known as Denisovans. (Via Natural History Museum, London)
"Interestingly the genome actually resembles more closely the genome found from Denisova Cave in Siberia. Now that's very unexpected. Siberia is a long way from Spain." (Via BBC)
The Denisovans were only discovered in 2010 when scientists analyzed the DNA of an 80,000-year-old pinkie-bone and molar. They're believed to be a sister family to the Neanderthal group. (Via The Independent)
So what does the discovery do for our understanding of human evolution?
According to National Geographic, it "scrambles" it.
A sentiment the co-author of the study seems to agree with. Quoted by International Business Times, he said, "Right now, we've basically generated a big question mark. … Our results suggest that the evolutionary history of Neanderthals and Denisovans may be very complicated and possibly involved mixing between different archaic human groups."
And according to The New York Times the surprising discovery may just be the tip of the iceberg. "It is possible, for example, that there are many extinct human populations that scientists have yet to discover. They might have interbred, swapping DNA."
That's yet to be determined, but scientists believe the remains could lead to new information on how human species evolved and spread. The study was published in the journal Nature.
